The invention relates to an adhesive tape for a flying reel change and to a splice method using such an adhesive tape, especially in paper converting machines, printing machines and the like.
The flying reel change is a common method, in paper mills or the like, to replace an old paper reel which has almost been unwound by a new one without having to stop the high-speed machines. In this case, double-sided self-adhesive tapes, so-called tabs, are used, which on the one hand are highly sticky and tacky but, on the other hand, because of their water-soluble self-adhesive compounds and paper carriers are not disruptive when the paper waste is reused in the papermaking machine. These tabs are stuck in an elaborate way in zig-zag form at the web start, a procedure which demands experienced specialist personnel, there remaining only about 4-5 minutes for the entire operation because of the high-speed machine.
Although this technology is tried and tested, it has some disadvantages. Thus, specialist personnel are needed, there is always frantic activity, and the bonds are also relatively thick, since in each case two paper layers and the adhesive tab between them are the result: a result which is not desired in the paper industry.
For this xe2x80x9cpointed bondingxe2x80x9d during a flying reel change, there are diverse products on the market, so-called tabs, which, in addition to a paper carrier, have a water-soluble self-adhesive compound coated on both sides. Such adhesive tapes are on the market, inter alia under the designation tesafix (Beiersdorf).
Numerous adhesive tapes for such purposes are described in the prior art. Thus, EP 418 527 A2 discloses a method of preparing a reel of web-like printing material for automatic reel changes and an adhesive strip suitable for this purpose. DE 40 33 900 A1 also describes an adhesive tape suitable for a splice point. However, adhesive areas which are exposed after a splicing method has been carried out are disadvantageous.
The non-adhesive covering of otherwise exposed adhesive areas is taught by U.S. Pat. No. 5,702,555 for more static loadings while securing a reel start, while DE 196 32 689 A2 discloses such an adhesive tape for dynamic loading during a splicing method, whose paper carrier cleaves and, with its remains, covers the adhesive compounds.
Also of this type is an adhesive tape according to DE 196 28 317 A1, likewise for a splicing method. This adhesive tape bears, on its non-adhesive rear side, a double-sided adhesive tape (6), which has a paper carrier (7) which is suitable for splicing and which cleaves (7a, 7b, FIG. 3) during the splicing method and covers the respective adhesives. This double-sided adhesive tape (6) ends at one side with one side of the paper carrier (2), is therefore arranged along one of the long edges of the adhesive tape.
In practice, these adhesive tapes also exhibit disadvantages, primarily because a splice does not succeed, but rather ends as a break, without any reason for this being visible.
The object of the invention was to provide a remedy here.
This is achieved by an adhesive tape and a splicing method as is characterized in more detail in the claims. In order to avoid repetitions, reference is expressly made to the claims, especially also to relevant preferred embodiments.
According to the invention, splices succeed without breaks, the central feature constituting the offset or the distance V provided of the double-sided adhesive tape DO from the long edge LK of the adhesive tape. This success by comparison with the prior art is shown by reference by comparative trials, which are presented in the table.
Cleavable Paper
The cleavable paper advantageously has a distinctly lower cleavage resistance than the paper carrier which has to accommodate the tensile forces. An adequate difference is helpful for the functional principle of the product according to the invention.
The cleavable papers considered are, for example, the following papers or paper composite systems:
Duplex papers: These papers are commercially available and are used, for example, in the manufacture of filter materials and wall coverings.
Easily cleavable papers: The adjustment of the cleavage work is carried out via the consolidation of the paper fibre structure. The lower the consolidation, the lower the cleavage work.
Suitable paper types are, for example, machine-finished papers calendered on one side or else highly-calendered kraft papers.
Sized paper systems: The cleavage work is adjusted via the chemistry of the adhesive size. The size should have penetrated into the paper only to an insignificant extent.
Clean cut edges are also helpful for the aims of the present invention. During the cutting operation, no compound should be squeezed out. In particular, the cleavable attachment area of the cleavable material should not be covered by contact adhesive compound.
The amount by which the cleavable material is set back, or the distance V, should be 0.5-15 mm according to the invention, especially 1-7 mm and quite particularly 1.5 mm-3.5 mm.
Diverse cleavable paper systems are considered for the cleavable paper, such as
Duplex papers (papers laminated together in a defined manner), the cleavage process proceeds extremely homogeneously, no stress peaks are produced, for example as a result of inhomogeneous consolidation. These papers are used for the manufacture of wall coverings and filters.
Easily cleavable paper systems
Highly consolidated papers sized together in a defined way ( papers with a high cleavage strength). Sizing can be carried out, for example, with starch, starch-containing derivatives, wall covering adhesives based on methylcellulose (Methylan (copyright), Henkel KGaA, Dxc3xcsseldorf) or else based on polyvinyl alcohol derivatives.
The width of the carrier of the cleavable paper is preferably 3-20 mm, especially 6-12mm.
The invention relates in one embodiment to an adhesive tape, characterized in that a slit (SC) is arranged at a distance of 20 to 40 mm from that of a long edge (LK 2) of the adhesive tape which is opposite a long edge (LK1) close to which the doublesided adhesive tape (DO) is arranged. The double-sided adhesive tape (DO) is 3 to 20 mm wide, especially 6 to 12 mm wide.
All basic types of contact adhesive compound are considered as the self-adhesive compounds, especially
acrylates (water-soluble and non-water-soluble)
natural rubber compounds, synthetic rubber compounds
The invention relates in one embodiment to a splicing method, in which an adhesive tape is partly stuck behind the top paper web of a reel of paper, while the double-sided adhesive-tape on the rear side of the adhesive tape is for its part stuck to the paper web beneath it and therefore secures the top paper web, firstly only part of the release material possibly located on the self-adhesive compound being pulled off, so that that part of the self-adhesive compound needed for the splicing method is still covered by release material and, in this state, the paper reel has no free adhesive area, after which, in order to prepare the splicing method finally, any remaining release material still present is removed, whereupon the new paper reel equipped in this way is placed beside an old paper reel which has been almost completely unwound and is to be replaced, and is accelerated to the same peripheral speed as tbe said old reel, is then pressed against the old paper web, the exposed self-adhesive compound of the adhesive tape sticking to the old paper web at essentially equal speeds of the paper webs, while at the same time the paper carrier of cleavable paper cleaves and, with its remains, covers both self-adhesive compounds which were coated on the said paper carrier, so that they are non-adhesive.
The splicing method, here the sticking using the splicing tape, can in particular be carried out in such a way that the adhesive tape is stuck to the running web at right angles (disadvantage: the cleavable paper system must cleave completely into secondary fractions), but also at an acute angle (advantage: the cleaving process runs as a wave through the adhesive tape), especially up to 25xc2x0, above all up to 15xc2x0.